JP-2026074722-A - Laser processing method

Abstract

[Problem] When using a diffractive optical element to focus and irradiate multiple branched beams from a laser beam onto a workpiece, the risk of defects occurring due to diffracted light of an order that does not contribute to processing being focused and irradiated onto the workpiece is reduced. [Solution] The laser processing method is a laser processing method that irradiates a laser beam onto a street set on an object to be processed, and comprises a branching step 1001 in which a diffractive optical element is used to branch the laser beam into a plurality of branched beams including processing light to irradiate the street and unwanted light to irradiate the device, and a focusing irradiation step 1002 in which the plurality of branched beams are each focused and irradiated from the surface side of the object to be processed, wherein the irradiation diameter of the area irradiated by one unwanted light, a branched beam, on the surface is set to be larger than the irradiation diameter of the area irradiated by one processing light, a branched beam. [Selection Diagram] Figure 4

Inventors

• 大町 修

Assignees

• 株式会社ディスコ

Dates

Publication Date

20260507

Application Date

20241021

Claims (3)

1. A laser processing method in which a laser beam is irradiated onto a processing area set on an object to be processed, A branching step in which the laser beam is branched into a plurality of branched beams including processing light to irradiate the processing area and unwanted light to irradiate the non-processing area using a diffractive optical element, The system includes a focusing irradiation step in which each of the multiple branched lights is focused and irradiated from one side of the object to be processed, A laser processing method in which, on the surface, the irradiation diameter to which one unwanted light is irradiated is set to be larger than the irradiation diameter to which one processing light is irradiated.
2. The laser processing method according to claim 1, wherein the energy density of one unwanted light beam irradiated onto the unprocessed area on the surface is less than the energy density required to alter the unprocessed area.
3. The object to be processed comprises a plurality of streets on one surface and device areas demarcated by these streets, The laser processing method according to claim 1 or claim 2, wherein the processing area is set on the street and the non-processing area is set on the device area.

Description

This invention relates to a laser processing method. A laser processing apparatus has been proposed that uses a diffractive optical element and a focusing lens to split a single laser beam into multiple laser beams and focus them, then irradiates a processing line (processing area) with these multiple laser beams to simultaneously perform multiple linear processing steps (see, for example, Patent Document 1). In the optical system that branches a laser beam using a diffractive optical element as shown in Patent Document 1, in addition to the light of the order that is irradiated onto the processing area and contributes to processing, higher-order light and zero-order light that are not irradiated onto the processing area and do not contribute to processing are also generated. Japanese Patent Publication No. 2018-181938 Figure 1 is a schematic perspective view showing an object to be processed by the laser processing method according to Embodiment 1.Figure 2 is a perspective view showing an example of the configuration of a laser processing apparatus for implementing the laser processing method according to Embodiment 1.Figure 3 is a schematic diagram showing the configuration of the laser beam irradiation unit and other components of the laser processing apparatus shown in Figure 2.Figure 4 is a flowchart showing the flow of the laser processing method according to Embodiment 1.Figure 5 is a schematic diagram showing the state of laser processing of an object to be processed in the comparative example laser processing method.Figure 6 is a schematic diagram showing a partial cross-section of the laser processing of an object to be processed in a laser processing method according to a modified example of Embodiment 1.Figure 7 is a schematic diagram showing in a partial cross-section another state in which the workpiece is laser processed in the laser processing method according to a modified example of Embodiment 1. The embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Furthermore, the components described below include those that are easily conceivable to those skilled in the art, and those that are substantially the same. Moreover, the components described below can be combined as appropriate. In addition, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention. [Embodiment 1] A laser processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. Figure 1 is a schematic perspective view showing an object to be processed by the laser processing method according to Embodiment 1. Figure 2 is a perspective view showing an example of the configuration of a laser processing apparatus for carrying out the laser processing method according to Embodiment 1. Figure 3 is a schematic diagram showing the configuration of the laser beam irradiation unit and the like of the laser processing apparatus shown in Figure 2. Figure 4 is a flowchart showing the flow of the laser processing method according to Embodiment 1. Figure 5 is a schematic diagram showing the state of laser processing of an object in a comparative example laser processing method. (Object to be processed) The laser processing method according to Embodiment 1 is a method of laser processing (equivalent to laser processing) of the workpiece 200 shown in Figure 1. The workpiece 200 shown in Figure 1, which is the target of the laser processing method according to Embodiment 1, is a wafer such as a disc-shaped semiconductor wafer or optical device wafer with a substrate made of silicon, GaAs, InP, GaN, or SiC. As shown in Figure 1, the workpiece 200 comprises a plurality of intersecting streets 202 on a surface 201 (corresponding to one surface), and devices 203 (corresponding to device regions) formed in each region partitioned in a grid pattern by the streets 202. The devices 203 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors), MEMS (Micro Electro Mechanical Systems), or semiconductor memory (semiconductor storage devices). (Laser processing equipment) The laser processing method shown in Embodiment 1 is carried out using the laser processing apparatus 1 shown in Figure 2. Next, the laser processing apparatus 1 will be described. The laser processing apparatus 1 is a processing apparatus that laser processes a workpiece 200. As shown in Figure 2, the laser processing apparatus 1 comprises a holding unit 10, a moving unit 30, a laser beam irradiation unit 20, an imaging unit 40, and a control unit 100. The holding unit 10 is disc-shaped, and a flat holding surface 11, oriented horizontally to hold the workpiece 200, is formed fro